Many downhole applications require adjacent components to remain in a fixed relationship during run in. In many cases, shear pins or other temporary restraints are employed to break away under an applied force. While in many situations such arrangements work reasonably well, there can be situations during run in that could trigger a premature failure of the shear locking mechanism. Such early and unintended release of a shear retainer could have the result of an inability to set the tool or operate the tool where needed. It has been learned that in some applications, the process of running a tool into the desired location can put cyclical stresses on shear pins so as to cause them to fail prematurely.
The desire to prevent premature shear pin failure has brought about the solution offered by the present invention. The problem that lead to the present invention was first noticed in a product called CMP Defender®, which is a product made by Baker Hughes and features a mandrel and an interior sliding sleeve. This tool was described in U.S. application Ser. No. 10/408,798 filed on Apr. 7, 2003, whose contents are fully incorporated herein as if fully set forth. It also has an exterior sliding sleeve that is covering a port in the mandrel during run in. The interior sleeve is in the open position for run in. Pressurizing the tubing sets the packer, which can be connected to this tool. After sufficient pressure is developed, the packer sets. The application of pressure shifts the outer sleeve down to still leave the mandrel port closed as long as pressure that set the packer is maintained. However, the initial pressurizing that shifts the outer sleeve down breaks a shear pin that held it fixed for run in. When the packer setting pressure is removed, a spring moves the outer sleeve uphole to open the mandrel port.
The problem with this design was that during run in the string is lowered and brought to an abrupt stop to add new tubing at the surface. The abrupt change in direction caused the outer sleeve to stress the shear pins and created a potential that the shear pin could prematurely fail before the packer was delivered to its intended location.
Various solutions were devised and described below. Those skilled in the art will realize that the solutions are adaptable to other devices than the tool described. Sliding sleeve valves have long been known in the art as illustrated in U.S. Pat. Nos. 5,156,220 and 6,260,616 . Locking devices involving dogs extending into grooves and supported to lock one body to another are illustrated in U.S. Pat. No. 4,510,995 and 4,823,872 . Those skilled in the art will appreciate the various solutions offered by the present invention to address the issue of stressing the retaining mechanism during run in so that the components will remain in position until relative movement is needed to set the tool, from a review of the description of the various embodiments, the drawings and the claims, which appear below.